Ice jam intel: How the Athabasca River ice buildup is flooding Fort McMurray

Ice jams can stretch for kilometres, reach several metres in height and cause rivers to rise in a matter of hours, says one river ice expert.

An ice dam roughly 25 kilometres long on the Athabasca River flooded downtown Fort McMurray, Alta., and forced 13,000 people out of their homes this week.

Another ice jam on the Peace River estimated to be almost 40 kilometres has ousted 450 people from the hamlet of Fort Vermilion.

“The length can be many kilometres long,” University of Saskatchewan associate professor Karl-Erich Lindenschmidt said Wednesday.

“The ice can back up a long distance upstream. Some rivers, I’ve seen sometimes maybe six metres (in thickness) at the toe, at the lodgment. That’s where the greatest concentration of the ice accumulation is.”

Lindenschmidt developed an ice jam flood forecasting system, which he tested on the Athabasca in 2018. He’s also worked with Manitoba government on Red River flood modelling.

Mayor Don Scott of the Regional Municipality of Wood Buffalo, which includes Fort McMurray, considered blowing up the Athabasca ice jam with explosives but ultimately decided against it after hearing from experts.

The mayor said that method was used in 1977.

“We talked about the potential for military intervention on the ice itself,” Scott said this week.

“It’s the sheer size of the ice jam itself that really prevents the military from using explosives or CF-18s.

“There have been a lot of suggestions. Apparently none of them are workable in this situation. We’re going to be waiting on Mother Nature for awhile.”